Grant: Operating Grant

Injection drug use accounts for the majority of new cases of Hepatitis C virus (HCV) infections and for 30% of all new cases of AIDS in Canada. Despite considerable prevention efforts, HIV incidence in Montreal injection drug users (IDUs) remains among the highest for North American cities, and studies have shown modest or no effect of HIV prevention programs on HCV transmission. In Montreal, up to one in three IDU will contract HCV in the next year, and these figures do not include re-infections. There is a crucial need to estimate the true burden of HCV infection among IDUs and to better assess the determinants of HCV/HIV infections to improve prevention efforts. We recently demonstrated that high-risk injection behaviour among IDUs living in Montreal was associated with neighbourhood educational attainment and low income, and that IDUs living in socioeconomic disadvantaged areas or with a high level of crimes were at higher risk of acquiring HCV. Cumulative duration of injection appeared to influence such relationships. Following acute infection, approximately 26% of recently infected individuals spontaneously clear HCV. Hence, a key question for future HCV vaccine development is whether protective immunity against HCV occurs after HCV clearance. This renewal application seeks to further investigate how individual and contextual factors constitute key potential influences that may exacerbate or attenuate the rate of viral transmission, thereby presenting opportunities for intervention. We will also expand the scope of our research by studying the course of HCV infection, including primary infection, re-infection and clearance among injection drug users.